Smoke suppressing and fire retarding are two different phenomena and have no direct interrelation. For example, fire retardants are designed to retard combustion under conditions at which combustion normally occurs; while smoke suppressants are designed to reduce the amount of smoke evolved once combustion has started.
Fire retardancy for plastics is a fairly well developed technology, but the art has previously been relatively unconcerned with smoke. Indeed, some resins or plastics can actually produce more smoke when some fire retardants are present than when they are absent. For example, in an article entitled "Method for Measuring Smoke from Burning Materials" by Gross et al, which appeared in "ASTM Special Technical Publication 422", pages 182 and 183, a glass-reinforced polyester is reported as having a maximum smoke, Dm, hereinafter defined, of 395; while a glass-reinforced polyester that contained a flame retardant had a Dm of 618. Further, in Business Week for Mar. 10, 1973, pages 130N and 130P, it is reported that while new FAA rules tighten limits on flammability of materials, they say nothing regarding the generation of smoke or toxic fumes. Moreover, according to the cited article, new fireretardant synthetics that have been developed to meet such rules actually smoke more than their predecessors. Copolymers of acrylonitrile-butadienestyrene are reported to produce the densest smoke of all plastics tested, while polyvinyl polymers produce the most acrid smoke, especially polyvinyl materials that have been chlorinated to improve their fire resistance.
First attempts to control the burning of plastic materials were unconcerned with the smoke problem. There is little or no existing technology of smoke suppressants applicable to organic resinous materials such as the usual synthetic plastics.